Excessive contraction of the digestive tract during endoscopic examination of the digestive tract such as stomach and large intestine prevents correct diagnosis and allows a minute lesion such as a small-sized carcinoma to be missed.
As a contraction inhibitor for endoscopic examination of the digestive tract, an anti-cholinergic agent scopolamine butylbromide (Trade name: Buscopan Injection, Nippon Boehringer Ingelheim Co., Ltd.) or glucagon has conventionally been prescribed. However scopolamine butylbromide is contraindicated in a patient with glaucoma, prostatic hypertrophy, or arrhythmia, and glucagon has some problems including its very weak effect in inhibition of digestive tract contraction. Scopolamine butylbromide has to be injected immediately before or during the examination because it is to be injected intravenously or intramuscularly.
In addition some of the formulations may cause disorder of accommodation or vertigo after administration, so that the person who received administration of such a formulation for the examination should refrain for example from driving a car for a while after completion of the examination.
Accordingly, in an attempt to solve the problems mentioned above, an investigation was made recently to produce a digestive tract contraction inhibitor formulation using peppermint oil (Gastrointestinal Endoscopy, Vol. 53, No. 2, 172-177 (2001).
For production of formulations of such an inhibitor, the conventional methods disclosed include a method in which peppermint oil and water are mixed by stirring and allowed to stand at room temperature for 24 hours and only the transparent portion after elimination of the oily component floating on the surface of the water is used, and a method in which after mixing by stirring and standing at room temperature for 24 hours, an aqueous layer is filtered to remove an oily component before use. The formulations produced by these methods, however, have a risk of loss of the volatile peppermint oil by evaporation while standing at room temperature for a long time, and thus have a problem that the content of peppermint oil at the time of administration to a patient may be inconstant or indefinite. Consequently a constant amount of a conventionally-formulated product may fail to produce a constant effect when administered for example by spraying as a gastric contraction inhibitor onto the wall of stomach, which results in an insufficient inhibitory effect on contraction. Furthermore, these products require formulation just before use because of their difficulty in long-term storage and the quality of the formulation may be variable from site to site of medical practice.